Organic EL elements are optical semiconductor devices which have been increasingly used as backlights in liquid crystal displays and self-luminous thin flat-panel display devices. However, the organic EL elements are much more likely to be deteriorated when exposed to moisture and oxygen. More specifically, the metal electrode and organic EL layer separate from each other at their interface by the impact of moisture; metal is oxidized to cause an increase in resistance; the property of light-emitting materials contained in the light-emitting layer of the organic EL element is altered by moisture; and so forth. For these reasons, organic EL elements have the drawbacks of the loss of luminescence and/or reduced luminance. Moreover, in optical semiconductors such as inorganic LEDs, electric circuits and/or the like connected to optical semiconductors may sometimes deteriorate when they are exposed to moisture and others.
In an effort to solve the foregoing drawbacks, numerous methods have been proposed for protecting optical semiconductors such as organic EL elements from moisture and oxygen. One method involves laminating an organic EL sealant layer, which contains (A) a compound having a glycidyl group and (B) an acid anhydride curing agent as main components, onto an organic EL element (for surface sealing) and then attaching glass or film (see, e.g, Patent Literature 1).
Due to its susceptibility to degradation by moisture and/or oxygen, the organic EL element is often sealed with a laminate film formed of a resin layer made of resin and an inorganic compound layer made of inorganic compound. There are two types of methods for sealing an organic EL element with a laminate film: 1) an organic EL element is covered with an inorganic compound layer and thereafter further with a resin layer, and 2) an organic EL element is covered with a resin layer and thereafter further with an inorganic compound layer (see Patent Literature 2).
As sealants for photosensors, LEDs and/or other devices, epoxy resin compositions have been proposed that contain a compound represented by Zn(CnH2n+1COO)2 and an imidazole compound serving as a curing accelerator (see, e.g., Patent Literature 3). Further, as powder coating materials, compositions containing a metal complex have been proposed wherein an amine compound and a carboxylate are coordinated with a metal ion such as a zinc ion (see, e.g., Patent Literature 4).